Electrochemical Reactions of Iodine Molecules Encapsulated in Single-Walled Carbon Nanotubes

We prepared iodine molecules encapsulated in single-walled carbon nanotubes (I@SWCNTs) by electro-oxidation of iodide ions with empty SWCNT electrode. Li-ion battery electrode properties of I@SWCNTs were investigated. It was found that the I@SWCNT sample can catch and release Li ions reversibly. We performed Raman measurements to reveal the Li-ion storage mechanism of I@SWCNT. It is plausible that chemical reactions of I₂ from/into LiI in SWCNTs occur during Li-ion charging/discharging of I@SWCNT. We also prepared the CsI@SWCNT sample to verify that alkali metal ions can be extracted from alkali metal halide in SWCNTs. The extraction of cesium ions from CsI@SWCNT was confirmed by Raman measurements. It was also found that I@SWCNT can work as a Li-ion battery electrode in solid electrolyte as well.